[PATCH -mm -v8 1/3] Add Kconfig option ARCH_HAVE_NMI_SAFE_CMPXCHG

[Huang Ying <ying.huang@intel.com>]

cmpxchg() is widely used by lockless code, including NMI-safe lockless
code.  But on some architectures, the cmpxchg() implementation is not
NMI-safe, on these architectures the lockless code may need to a
spin_trylock_irqsave() based implementation.

This patch adds a Kconfig option: ARCH_HAVE_NMI_SAFE_CMPXCHG, so that
NMI-safe lockless code can depend on it or provide different
implementation according to it.

On many architectures, cmpxchg is only NMI-safe for several specific
operand sizes. So, ARCH_HAVE_NMI_SAFE_CMPXCHG define in this patch
only guarantees cmpxchg is NMI-safe for sizeof(unsigned long).

Signed-off-by: Huang Ying <ying.huang@intel.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
CC: Richard Henderson <rth@twiddle.net>
CC: Russell King <linux@arm.linux.org.uk>
CC: Mikael Starvik <starvik@axis.com>
CC: David Howells <dhowells@redhat.com>
CC: Yoshinori Sato <ysato@users.sourceforge.jp>
CC: Tony Luck <tony.luck@intel.com>
CC: Hirokazu Takata <takata@linux-m32r.org>
CC: Geert Uytterhoeven <geert@linux-m68k.org>
CC: Michal Simek <monstr@monstr.eu>
CC: Ralf Baechle <ralf@linux-mips.org>
CC: Kyle McMartin <kyle@mcmartin.ca>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Chen Liqin <liqin.chen@sunplusct.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Ingo Molnar <mingo@redhat.com>
CC: Chris Zankel <chris@zankel.net>
---
 arch/Kconfig         |    3 +++
 arch/alpha/Kconfig   |    1 +
 arch/avr32/Kconfig   |    1 +
 arch/frv/Kconfig     |    1 +
 arch/ia64/Kconfig    |    1 +
 arch/m68k/Kconfig    |    1 +
 arch/parisc/Kconfig  |    1 +
 arch/powerpc/Kconfig |    1 +
 arch/s390/Kconfig    |    1 +
 arch/sh/Kconfig      |    1 +
 arch/sparc/Kconfig   |    1 +
 arch/tile/Kconfig    |    1 +
 arch/x86/Kconfig     |    1 +
 13 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index f78c2be..8dea68d 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -178,4 +178,7 @@ config HAVE_ARCH_JUMP_LABEL
 config HAVE_ARCH_MUTEX_CPU_RELAX
 	bool
 
+config ARCH_HAVE_NMI_SAFE_CMPXCHG
+	bool
+
 source "kernel/gcov/Kconfig"
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 943fe69..4252a77 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -7,6 +7,7 @@ config ALPHA
 	select HAVE_SYSCALL_WRAPPERS
 	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select HAVE_DMA_ATTRS
 	help
 	  The Alpha is a 64-bit general-purpose processor designed and
diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig
index 313b130..1fc9bf8 100644
--- a/arch/avr32/Kconfig
+++ b/arch/avr32/Kconfig
@@ -6,6 +6,7 @@ config AVR32
 	select HAVE_CLK
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	help
 	  AVR32 is a high-performance 32-bit RISC microprocessor core,
 	  designed for cost-sensitive embedded applications, with particular
diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
index 77deacd..01b5adb 100644
--- a/arch/frv/Kconfig
+++ b/arch/frv/Kconfig
@@ -5,6 +5,7 @@ config FRV
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 
 config ZONE_DMA
 	bool
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index e0f5b6d..2cacfa7 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -22,6 +22,7 @@ config IA64
 	select HAVE_KVM
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_DMA_API_DEBUG
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	default y
 	help
 	  The Itanium Processor Family is Intel's 64-bit successor to
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index bc9271b..8259bd1 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -4,6 +4,7 @@ config M68K
 	select HAVE_AOUT
 	select HAVE_IDE
 	select GENERIC_ATOMIC64
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG if RMW_INSNS
 
 config MMU
 	bool
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index ca59250..79a3560 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -11,6 +11,7 @@ config PARISC
 	select BUG
 	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select GENERIC_ATOMIC64 if !64BIT
 	select GENERIC_HARDIRQS_NO__DO_IRQ
 	help
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9d44ad3..56a57ea 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -145,6 +145,7 @@ config PPC
 	select GENERIC_ATOMIC64 if PPC32
 	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_HW_BREAKPOINT if PERF_EVENTS && PPC_BOOK3S_64
 
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index c05d081..d3ff45d 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -82,6 +82,7 @@ config S390
 	select INIT_ALL_POSSIBLE
 	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_BZIP2
 	select HAVE_KERNEL_LZMA
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 84d8c87..a48f6fb 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -11,6 +11,7 @@ config SUPERH
 	select HAVE_DMA_ATTRS
 	select HAVE_IRQ_WORK
 	select HAVE_PERF_EVENTS
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
 	select PERF_USE_VMALLOC
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_BZIP2
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index af40adf..8b70990 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -22,6 +22,7 @@ config SPARC
 	select RTC_CLASS
 	select RTC_DRV_M48T59
 	select HAVE_IRQ_WORK
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select HAVE_DMA_ATTRS
 	select HAVE_DMA_API_DEBUG
 	select HAVE_ARCH_JUMP_LABEL
diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index e11b5fc..b8ebec6 100644
--- a/arch/tile/Kconfig
+++ b/arch/tile/Kconfig
@@ -104,6 +104,7 @@ config TILE
 	select GENERIC_FIND_NEXT_BIT
 	select USE_GENERIC_SMP_HELPERS
 	select CC_OPTIMIZE_FOR_SIZE
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 
 # FIXME: investigate whether we need/want these options.
 #	select HAVE_IOREMAP_PROT
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fe0bdb4..1b01117 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -23,6 +23,7 @@ config X86
 	select HAVE_OPROFILE
 	select HAVE_PERF_EVENTS
 	select HAVE_IRQ_WORK
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG if !M386
 	select HAVE_IOREMAP_PROT
 	select HAVE_KPROBES
 	select HAVE_MEMBLOCK
-- 
1.7.2.3